Table 2: Grade index for element 105 damage state.

ParameterN1 (intact)N2 (minor damage)N3 (moderate damage)N4 (severe damage)

Change of deflection (mm)0–33–88–1515–30
Change of strain (ε)0–0.0010.001–0.0030.003–0.0080.008–0.02
Predict damage values by SVM0–0.050.05–0.1
0.1–0.50.5–1
Modal curvature rate0–0.10.1–0.250.25–0.60.6–1